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3D printing with silicone — is its time coming?

Material science in additive manufacturing is rapidly evolving, largely in order to meet the increasingly sophisticated requirements of AM specialists and their clients. One especially intriguing development is the fulfilment of one of additive manufacturers’ long-held dreams: 3D printing with silicone. While the potential advantages of this approach have been obvious for many years, it is only recently that the available technology has evolved to the point where it could potentially become feasible.

 

Why silicone?

Silicone is already a versatile and well-established material, used across different industries in a wide variety of applications. For example, it can be used in any mechanical component where flexibility must be combined with strength and durability. These qualities are also ideal for the fashion industry, where it can be used to create sophisticated ornamentation, or practical elements, like shoe inserts. It is also a popular choice for medical and food-safe parts.

So why has it not become a standard tool for additive manufacturing?

Unfortunately, the reality is that 3D printing with silicone has proven difficult, if not impossible, until relatively recently. The material’s natural viscosity makes it difficult to extrude cleanly and limits the sort of geometries that can be printed accurately. But there’s good news: thanks to the ongoing efforts of researchers and material specialists, a production-worthy approach to 3D printing with silicone may soon be available.

 

The evolving technology

One of the first viable technologies for printing with silicone was the Picsima process, which was originally launched in 2012 by Fripp Design and Research in Sheffield, with a patent awarded in 2016. The Picsima process works by applying a catalyst agent via a needle-thin extruder to create solid structures within a bath of silicone oil, with no need for support structures. While the technology promises to deliver high-quality medical prostheses, based on 3D scans, it is not yet commercially available for large-scale applications.

ACEO® — a division of Wacker Chemie — recently announced their new technology for 3D printing with silicone, which is being explored at their Open Print Lab in Germany. This method places droplets of silicone on the printing area, which are then cured with UV light to create solid structures, delivering parts with similar mechanical qualities to injection-moulded ones.

As with the Picsima method, ACEO®’s technology requires the use of specialist printers (ACEO® Imagine models, in this case) and software that has been fully optimised to manage the new material’s unique chemical and mechanical properties. While it still requires the use of support structures, ACEO® have developed their own soluble support material, which will allow highly complex geometries to be successfully printed, while avoiding the time-consuming step of manually removing supports during post-processing.

Not long after, Keyence, another German company, announced their own silicone-based materials for 3D printing, which they refer to as ‘rubbery elastomers’. These were designed specifically to work with their Agilista series of printers, which use an inkjet-based approach. Unfortunately, at this point, the technology is only available in Germany and Japan due to patent restrictions.

A different approach to silicone printing was unveiled by the North Carolina State University in June 2017. This approach combines water with liquid silicone rubber to allow for the creation of flexible structures using tiny silicone rubber beads. NCSU staff are already envisioning the potential applications for this technology in the medical sector, such as printing flexible bandages onto patients’ bodies.

 

What’s next for silicone in the world of additive manufacturing?

All these methods are promising great things, and based on what we’ve seen so far, have a huge amount of potential. However, as with any new technology, the ultimate test of their viability will be how successfully they can be folded into production workflows. We would envisage new hybrid processes evolving around silicone printing, in which it can find specialist niches to support and enhance other technologies. Intriguingly, Fripp Design and Research have already been thinking along these lines with the Picsima process, suggesting that it could be used to print flexible prototypes of prostheses to test the fitting. Once it’s confirmed that a design fits the patient comfortably, that prototype can be used to create a mould for the final version.

We will be following these new technologies with interest, and look forward to seeing the ways manufacturers and AM specialists are able to take advantage of the possibilities they offer.